Detention Pond: Detailed Definition
A detention pond is an engineered basins constructed to manage stormwater runoff. It temporarily holds and retains a specific volume of rainwater and surface runoff, releasing it slowly to prevent flash flooding and reduce the impact on downstream systems. Unlike retention ponds that maintain a certain water level consistently, detention ponds are dry most of the time and only fill during periods of excessive rainfall.
Examples
-
Urban Development: In a new residential subdivision, a detention pond is built to manage the increased runoff caused by impervious surfaces like roads, roofs, and driveways. During a heavy storm, the pond collects runoff, reduces peak discharge rates, and minimizes the risk of urban flooding.
-
Commercial Area: A shopping center installs a detention pond to manage stormwater runoff from its large parking area. The pond collects rainwater, which otherwise could overwhelm the stormwater infrastructure, thereby protecting adjacent properties from water damage.
Frequently Asked Questions (FAQs)
Q1: How does a detention pond work?
- A1: A detention pond collects stormwater during periods of heavy rain and drains it slowly through a controlled outlet structure. This delay in drainage helps manage the rate at which water enters downstream water bodies, reducing the risk of flooding.
Q2: How is a detention pond different from a retention pond?
- A2: A detention pond is designed to temporarily hold water and remains dry between storms, whereas a retention pond maintains a permanent pool of water and releases excess stormwater gradually.
Q3: Are there any maintenance requirements for detention ponds?
- A3: Yes, regular maintenance is crucial, including removal of debris, ensuring the outlet structures remain clear, and periodic inspections to check for erosion or other damages.
Q4: What are the typical sizes of detention ponds?
- A4: The size of a detention pond varies depending on the local rainfall data, the catchment area size, and specific regulatory requirements. It can range from small basins in residential areas to large structures in industrial zones.
Q5: Do detention ponds have environmental benefits?
- A5: Beyond flood control, detention ponds help improve water quality by allowing sediments and pollutants to settle before the water is discharged.
-
Retention Pond: A retention pond is a graduated depression designed to capture and store rainwater permanently, releasing the surplus through an over-dam or controlled system slowly.
-
Stormwater Management: Techniques and strategies employed to manage the quantity and quality of stormwater runoff to prevent flooding and maintain water quality.
-
Floodplain: A generally flat area of land adjacent to a stream or river that experiences periodic flooding.
-
Impervious Surface: Surfaces that do not allow water to penetrate, causing runoff during rains, such as paved roads, parking lots, and building rooftops.
Online Resources
- U.S. Geological Survey (USGS) - Information on water resources and stormwater management.
- Environmental Protection Agency (EPA) - Guidelines and regulations related to water infrastructure and stormwater systems.
- American Society of Civil Engineers (ASCE) - Resources and policy papers on civil engineering aspects of water retention and flood control.
References
- EPA, “National Management Measures to Control Nonpoint Source Pollution from Urban Areas.”
- USGS, “Techniques and Methods to Manage Urban Flooding.”
Suggested Books for Further Studies
- “Stormwater Management for Smart Growth” by Bruce K. Ferguson
- “Design Hydrology and Sedimentology for Small Catchments” by Calvin B. Hutchison and J. Kent Solomon
- “Urban Water Infrastructure: Planning, Management, and Operations” by Purushotham Tukdeo and Shrikant Gautam
Real Estate Basics: Detention Pond Fundamentals Quiz
### What primary function does a detention pond serve?
- [x] Flood control by temporarily holding and slowly draining water.
- [ ] Providing a permanent water source.
- [ ] Housing aquatic wildlife year-round.
- [ ] Managing sewage waste.
> **Explanation:** A detention pond is primarily designed for flood control by temporarily holding runoff water and releasing it slowly to prevent immediate flooding downstream.
### Which type of pond remains dry between storm events?
- [x] Detention pond
- [ ] Retention pond
- [ ] Both
- [ ] Neither
> **Explanation:** Detention ponds are designed to remain dry most of the time and only hold water temporarily during storm events. Retention ponds, in contrast, always maintain a pool of water.
### What is a crucial part of maintenance for detention ponds?
- [x] Regular removal of debris.
- [ ] Checking the water pH levels.
- [ ] Providing year-round aquatic habitats.
- [ ] Ensuring the water is continuous.
> **Explanation:** Regular removal of debris is essential to ensure the inlet and outlet structures function properly, thereby preventing clogs and ensuring efficient drainage.
### What kind of environmental benefit can detention ponds provide?
- [x] Pollutant removal
- [ ] Continuous irrigation source
- [ ] Raising fish and other aquatic animals
- [ ] Providing drinking water
> **Explanation:** Detention ponds can improve water quality by allowing pollutants and sediments to settle before the water is gradually released.
### Detention ponds contrast with what other type of stormwater management pond?
- [x] Retention pond
- [ ] Filtration pond
- [ ] Absorption pond
- [ ] Sediment pond
> **Explanation:** Detention ponds are mainly compared to retention ponds, which maintain a permanent water level as opposed to temporarily holding water like detention ponds.
### Which of the following best describes an impervious surface?
- [x] A surface that does not allow water to penetrate.
- [ ] A surface made of permeable materials.
- [ ] A surface used for agricultural purposes.
- [ ] A surface that allows water to absorb quickly.
> **Explanation:** Impervious surfaces, such as pavement or roofing, do not allow water to penetrate and create runoff, increasing the need for stormwater management structures like detention ponds.
### What is the primary concern that necessitates constructions of detention ponds in urban areas?
- [x] Runoff from impervious surfaces can overwhelm stormwater systems causing floods.
- [ ] Stormwater provides insufficient drinking water.
- [ ] They are required to provide water for agriculture.
- [ ] They help attract tourism by providing aquatic activities.
> **Explanation:** Impervious surfaces in urban areas increase runoff, which can overwhelm stormwater systems, so detention ponds are necessary to manage and mitigate this runoff.
### How is the water released from a detention pond?
- [x] Slowly through a controlled outlet structure.
- [ ] All at once during major floods.
- [ ] It is held permanently without release.
- [ ] Evaporation when the pond is dry
> **Explanation:** The water in a detention pond is released slowly through a controlled outlet structure to mitigate flooding risks downstream.
### During which kind of weather events are detention ponds utilized most?
- [x] Heavy rainfall and storms.
- [ ] Drought periods.
- [ ] Regular weather conditions.
- [ ] During snow melt.
> **Explanation:** Detention ponds are primarily used during heavy rainfall and storms to manage excess runoff and prevent flooding.
### What maintenance routine is not typical for detention ponds?
- [ ] Regular inspection for erosion.
- [x] Maintaining permanent water levels.
- [ ] Checking outlet structures for clogs.
- [ ] Removing accumulated debris.
> **Explanation:** Detention ponds are designed to be dry between storm events, so maintaining permanent water levels is not typical for their routine maintenance.
